1. Field of the Invention
The present invention relates to apparatus for adjusting line endings upon text playback by a typewriter with text storage capability.
2. Statement Regarding the Art
Various techniques have been developed for selecting line ending points when playing back text strings from typewriter associated storage, such a capability being important to accommodate expansions and contractions in the text that result from editing. This problem of line adjustment arises frequently because document editing generally causes text shifts which propagate through the document and make necessary a new set of carrier return decisions to define a right margin.
The usual approach to solving the line adjustment problem involves the establishment of a return zone of, for example, five spaces immediately ahead of the right margin setting, and logic is provided for inserting a carrier return at the first inter-word opportunity occurring after the start of such zone (e.g., at the first subsequent space in the text string). If a long word starts just before the return zone, it may extend beyond the right margin setting and typically logic is provided to stop playback in the event of such occurrence. The operator then decides either to hyphenate the word or to play it out so as to extend beyond the right margin.
The above-described technique is somewhat inconvenient for automatic playback. It would be desireable for the operator to be free to leave the work area while a document is being printed from text storage. If occasional hyphenation decisions are required, however, the operator must be available to make those decisions and document printing is suspended during any period when the decision request is unanswered. To reduce the inconvenience of such stoppages, some typewriters have been provided with variable width return zones so that the operator may choose a wide return zone to lessen the occurrences of operator decision situations. Such an approach will result in a less uniform right margin, however, particularly where logic is not provided to search for the last possible line return opportunity within the return zone.
A slightly different approach for defining line endings is taken with video document displays. Typically, a return zone is not established for such systems but, rather, the first break point prior to the absolute right margin is utilized and subsequent text is moved to the following line. Such an approach avoids any need for operator intervention but does not provide the potential for uniformity of the right margin that is possible using a typewriter where excursions on either side of a reference right margin point are permitted.
It is also known to allow the operator to, in effect, scan the text prior to printing and insert hyphens wherever needed to control line endings.
Some printing systems achieve line end uniformity by changing interword or even intercharacter spacing, but such an approach requires rather sophisticated logic for controlling print point shifts.
While various line adjustment techniques are known, as indicated above, improved line adjustment is desirable to permit unattended playback operation of the typewriter with a minimum of loss of right margin uniformity. Also, it is desirable to provide an adjustment system that does not require selective variation of interword spacing.